Traffic controlling system for railroads



April 5, 1932. N. D. PRESTON TRAFFIC CONTROLLING SYSTEM FOR RAILROADSFiled July 3, 1950 the trailing Patented Apr. 5, 1932 UNITED STATESPATENT OFFICE NEIL D. PRESTON,

OF ROCHESTER, NEW YORK, ASSIGNOR TO GENERAL RAILWAY SIGNAL COMPANY, OFROCHESTER, NEW YORK TRAFFIC CONTROLLING SYSTEM FOR RAILROADS Applicationfiled July 3,

This invention relates to traflic controlling systems or devices forrailroads, and more particularly to a safety device for spring switches.

In the well-known spring switch, the switch points are held in oneposition, usually the normal position, by a heavy spring which acts toreturn the points automatically to the normal position when the switchis 1 trailed, a suitable oil dash-pot or the like being usually employedto retard such return movement and prevent shifting and pounding of theswitch points as the successive wheels of a train pass through theswitch in direction. Since the spring mechanism or some of itsconnections to the switch may be bent or broken, so that the switchpoints are not properly held and may be displaced by the wheels of thetrain and cause derailment, train movements over such a spring switch inthe facing direction should be made at low speeds. This frequentlycauses delays in train operation, which would be avoided if the trainscould move over a spring switch in the facing direction at normalspeeds.

In accordance with this invention, it is proposed to provide suitablemeans for detecting if the spring of a spring switch is acting to holdthe switch points in the normal position with a predetermined pressure,sufficient to permit train movements in the facing direction at highspeeds.

35 Stated more specifically, it is proposed to include a suitablepressure responsive circuit controlling means in the connections betweenthe switch points andthe spring acting on these points, and employ thiscircuit con- 4 trolling means to control a signal governing trailic overthe switch in the same direction, so that this signal may clear only ifa predetermined force of pressure is acting to hold the switch points.

Other characteristic features and advantages of the invention will be inpart apparent, and in part pointed out, as the description progresses.

In the accompanying drawings, Fig. 1 il- 0 lustrates diagrammaticallyone arrangement of devices and circuits, embodying the in- 1930. SerialNo. 465,611.

vention, applied to a spring switch of the usual construction;

Fig. 2 shows a longitudinal section of one specific form of the pressureresponsive circuit controlling means of this invention; and

Fig. 3 illustrates diagrammatically a modilied construction of thepressure responsive circuit controlling device.

Referring to Fig. 1, the switch SW is assumed to be of the usual andwell-known construction having an insulated front rod F, to which isconnected the usual spring and dashpot mechanism S, and the switch standor hand-throw device HT. In accordance with this invention, a suitablepressure responsive circuit controlling device A is included in themechanical connections between the spring mechanism S and the switchpoints. As illustrated diagrammatically in Fig. 1, this device A in theform shown is fastened to the front rod F, and is connected to the rodor bar 4 extending to the spring mechanism S. Any other desiredarrangement may be employed, so long as the pressure responsive device Adetects the pressure or force acting against the switch points.

Train movements over the switch SW are governed by a signal 1, which inturn is controlled by a line or signal relay 1 HD. This signal 1 isshown conventionally as a threeposition semaphore signal, but may be acolorlight signal, or a signal of any other suitable type. The linerelay 1 HD, as shown, is a neutral-polar relay, controlling thesemaphore l in the usual way through a neutral contact 5 and a polarcontact 6. Neutral home and distant relays and various otherarrangements of controlling circuits for the signal 1, in accordancewith recognized practice. may be employed.

The energizing circuit for the relay 1 HD, as partially shown, may betraced from (C), indicating a connection to the usual common wire,through the relay 1 HD, wire 7, front contact 8 of the usual detectortrack relay, wire 9, contacts 10 of the usual switch circuit controllerof the switch SW, these contacts being closed only in the normalposition of this switch, wire 11, through the pressure responsivecircuit controlling device A,

wire 12, front contact 13 of the track relay T1, and thence throughother various controlling contacts of a block signaling system (notshown), suited to the particular application of the switch, to asuitable source of current, connected to the common wire, of a selectedpolarity (indicated by the symbol Bi), so that the signal 1 may becaused to indicate caution or clear.

Referring to Fig. 2', which shows one specific form of a pressureresponsive circuit controlling means, a casting 15 of a generalcylindrical shape and constituting the supporting casing or housing ofthe device, is formed with a flange 15 to be bolted to the front rod F.In one end of the casting 15 is threaded an adjusting bolt or plug 16,which engages one end of a heavy coil spring 17. The other end of thespring 17 engages a circular head 18, guided in a cylindrical recess atthe end of the casting 15; and fixed to this head 18 is the rod or bar4:. which is connected to the spring mechanism S. A sleeve 19, ofsuitable insulated material, is fastened to the rod 1; and. secured tothis sleeve 19 is a metallic contact ring 20 co-operating' with springcontact fingers 21. These contact fingers 21 are attached to andsupported by insulated binding posts 22, which are supported in a cap23, secured by bolts 24 to the casting 15. A washer 25 of felt orsimilar material. forms a dirt-tight connection between the cap" 23 androd 4.

If the spring mechanism S is in proper order and is transmitting apressure or force. in the direction indicated by the arrow a in Fig. 2,to hold the switch points in the normal position, the parts are in theposition shown in Fig. 2, the spring 17 being compressed. and thecontact ring 20 engaging the contact finger 21 to establish anelectrical connection between the wires 11 and 12 and permitenergization of the relay 1 HD to clear the signal 1. If, however, theparts of the spring mechanism S are broken, or if for any other reason,a predetermined pressure is not being transmitted from the rod 4 to theswitch points, the spring 17 expands and opens the contacts 2021, and,causes signal 1 to indicate stop. The tension of the spring 17 is set bythe adjusting plug 16, so that when this spring is compressed, as shownin Fig. 2, the pressure acting on the switch points is sufficient topermit train movement over the switch in the facing, direction at thenormal running speeds.

Thus, if the signal 1 indicates clear, a train may safely pass over theswitch SV in the facing direction at full speed, since the usual switchcircuit controller contacts 10, being closed, show that the switchpoints are in the full normal position, and the contacts 20-2l beingclosed, show that a predetermined pressure or force, suflicient tocompress the spring 17, is acting to hold the switch points in thisnormal position.

In the modified construction shown in Fig. the rod 4, connected to thespring mechanism S, is formed with, or has attached thereto, a flatrectangular head 30, provided with a longitudinal slot 31 with enlargedends, the material of the head and its dimensions being selected andproportioned so that the two side portions of the head 30, on oppositesides of the slot 31 may be pressed together a short distance by apredetermined pressure, and will resume the normal position when thispressure is released. A bar or rod 32, connected to the switch points,is suitably fastened to one side portion of the head 30 in line with therod 4.

Supported in any suitable Way in the slot 31 of the head 30 is apressure-responsive circuit controlling device, comprising a carbonblock 33, metallic plates 34, bearing against opposite faces of thecarbon block, and insulated plates 35, the wires 11 and 12 of theenergizing circuit for the relay 1 HD being connected to the metallicplates 34.

WVhen the predetermined desired pressure is acting to hold the switchpoints, the side portions of the head 30 are forced togethersufliciently to compress the carbon block 33, lower its resistance, andpermit sufficient current to flow to energize the relay 1 HD. If,however, this predetermined pressure is not acting to hold the switchpoints, pressure is not applied to the carbon block 33, and itinterposes sufficient resistance in the energizing circuit for the relay1 HD to prevent thisrelay attracting its armature.

This modified construction of Fig. 3 is preferably provided with asuitable housing or casing (not shown) and in both arrangements, thewires 11 and 12 are flexible and suitably protected, so that the switchpoints may be shifted to the reverse position by the switch stand HT, orby a trailing train movement.

From the foregoing it can be seen that this invention provides means fordetecting if a predetermined and safe pressure is acting to hold thepoints of a track switch in the normal position. This detecting meansmay be employed in various ways to govern train movement over theswitch; and while this detecting means is especially applicable to aspring switch, it may be advantageously employed in connection with anyhand or power-operated track switch.

Various adaptations, modifications, and additions may be made in theparticular construction and arrangement of parts and circuits shown anddescribed without departing "from the invention.

What I claim is 1. In a railway trafiic controlling system, thecombination with a track switch, a signal governing trafiic over saidswitch, operating means for moving said switch to and holding spring,and means included tively closed only when said members are it in anormal position,

and circuit controlling means effecin the connection between saidoperating forced toward each other by a force greater means and theswitch points and responsive than that of said spring.

to the pressure transmitted by said operating means against the pointsof said switch for controlling said signal, whereby said signal iscaused to indicate stop unless the switch points are held in the normalposition by a predetermined pressure.

2. In a railway trafiic controlling system, the combination with a trackswitch, spring means tending to hold said switch in the normal position,a signal governing traflic in the facing direction over said switch, andmeans for causing said signal to indicate stop unless a predeterminedpressure is acting to hold the points of said switch in the normalposition.

3. In a railway trailic controlling system, the combination with a trackswitch, spring means to hold said switch in the normal position, asignal governing trafiic in the facing direction over said switch,pressure responsive means included in the connection between the switchpoints and said spring means for causing said signal to indicate stopunless a predetermined pressure is acting to hold the switch points intheir normal position.

4. In a railway trafiic controlling system, the combination with a trackswitch, spring means to hold said switch in the normal position, asignal governing trafiic in the facing direction over said switch, acircuit acting when opened to cause said signal to indicate stop, andcircuit controlling means in said circuit effectively closed only ifsaid spring means is acting to exert a predetermined pres sure to holdthe switch points in their normal position.

5. In a traflic controlling system, the combination with a track switch,means for op erating the switch, and circuit controlling means includedin the connection between said switch and its operating means, saidcircuit controlling means being responsive to the pressure acting tohold the switch points in one position.

6. In a device of the character described, the combination with a trackswitch, operating means for the switch, a pressure responsive circuitcontrolling device comprising, two members movable relatively only by apredetermined force, one of said members being connected to the switchpoints and the other to said operating means.

7. In a device of the character described, the combination with a trackswitch, operating means for the switch, two relatively movable members,one of said members being connected to the points of said switch, theother member being connected to said operating means, a spring tendingto move said members apart, means for adjusting the tension of said Intestimony whereof I aflix my signature.

NEIL D. PRESTON.

